A suspension joint of the type to which the present invention relates is described in U.S. Pat. No. 3,584,793. It is particularly adapted for medical apparatus since it is constructed to permit encapsulation in such a manner that closing shells or cups form only a single matching rotary joint. The mechanism itself s completely enclosed, to permit easy cleaning and prevent accretion of dust or contamination which is not permissible in medical surroundings. The structure as described has joint portions which form closed surfaces, such as circular surfaces which provide only a single rotary gap or crack between each other, all lying in one plane, to completely seal off the joint and the therein enclosed pins and other mechanisms to adjust counter balances and weights. The adjustment elements are accessible by severing the cover shells or cups.
The pivoting angle which can be obtained in such a structure can be about 360.degree., or as far as electrical supply conductors which pass through the joint permit. The joint elements must be manufactured as closed, comparatively complex structures, however, in order to permit an arrangement in which the exposed rotary gap or crack forms only a single circular joint and to provide, internally, the necessary attachment or bearing points for the spring-loaded balance rod, to balance the weight of an operating room light, or another heavy structure, attached to the pivot arm of the joint. The complex construction of the heads of the joint is costly and the assembly is complex.
It is an object of the present invention to provide a rotary joint to suspend a heavy weight, for example an operating room light, which is spring-loaded, which is simple to make, easy to install, and which has the advantages of the prior structure of being easily cleaned and of preventing accretion of dust, dirt or contamination thereon.
Subject matter of the present invention: Briefly, the pivot arm to which the weight is attached has secured thereto, preferably laterally, one or more pivot rods which, preferably, are in the form of elongated link rods. The pivot or link rods are pivotally connected to a support pin which, in turn, is fixedy secured to a bracket or support member extending essentially vertically, for example by being suspended from a ceiling structure. The pin, likewise, can carry a fixed link to eccentrically secure a balance rod which is spring-connected to the support member for the weight.
The rotary joint is simple to make and to assemble, and permits inexpensive manufacture. Theoretically, a pivoting range in excess of 360.degree. is possible if the electrical connections are removed. The joint can be readily closed off by an inexpensive and simple cover made of plastic. The cover can be in the form of semi-spherical shells, or a shell and a disk, or the like, thus resulting in only a narrow and easily maintained rotary junction. The plastic cover forms a clean neat closure for the joint. After removal of the cover, that is, either or both of the shells or disks which may be of any suitable material besides plastic, the interior components of the rotary joints are freely accessible. The cover can be assembled to the holding pin or pivot pin by means of a slit which, after assembly, is closed; the cover may also be made in shell or cup shape, with two identical parts which are fitted together.
The entire structure is readily stabilized if two link plates are used, located at diametrically opposite sides of the pivoting member which, usually, is a hollow cylinder. The link plates are povited coaxially about coaxial pins which can be joined together by similar fixed links secured, respectively, to the respective pivot pins.